"A research firm serving the mobile phone industry has published an 18-page whitepaper about open source licensing. Entitled 'GPLv2 vs. GPLv3', the paper examines the meteoric rise of open source software, and the forces that shaped each license, before concluding with an extremely detailed point-by-point comparison."

GPL compatibility is not a special compatibility it's the very normal compatibility we know from any other area.

"""

FSF doublespeak. For an organization which claims to take the moral high ground, they play the doublespeak game to a level which rivals the large multinationals.

"""

What you mean is that you can't relicense GPL code. But that's relicensing and not compatibility.

"""

More doublespeak.

No. I mean that if you are a GPLv3 project you can take code from, say, an Apache project without changing your license. But if you are an Apache project, you cannot incorporate the GPL'd project's changes to your code back into your code without changing your license. And if you try to argue that a project changing its license is no big deal, just consider a scenario in which GPL'd projects were required to change their license to use, say, BSD or MIT licensed code.

I really wish that some of the permissively licensed projects would temporarily add a "no copyleft" clause to their licenses just to make the point. Can you imagine the shock, horror, and outrage which would be elicited if permissively licensed projects ever decided that turnabout was fair play?

The cries of "It's not fair!" would be deafening, and you know it.

Edit: I should probably clarify that I am generally favorable to copyleft licenses, including GPLv2 and even GPLv3. But to ignore the fact that restrictive licenses like GPLv[23] are not good team players with the greater FOSS community is deceptive and counterproductive. GPLv[23] are good licenses for many use cases *despite* their warts. But they do *have* the warts.